Operating device for a blast valve in an air blast circuit breaker



1961 H. FORWALD 3,005,077

OPERATING DEVICE FOR A BLAST VALVE IN AN AIR BLAST CIRCUIT BREAKER Filed March 19, 1959 2 Sheets-Sheet 1 a: i o c 6\( A 5/5 7/ 10 A INVENTOR Hacakon Torn/a Zd BY 6/ flftomey.

Oct. 17, 1961 H. FORWALD 3,005,077

OPERATING DEVICE FOR A BLAST VALVE IN AN AIR BLAST CIRCUIT BREAKER Filed March 19, 1959' 2 Sheets-Sheet 2 Fig. 2

INVENTOR. Haakorz Fern/a Zd position. This sequence Svenska Elektriska Aktiebolaget, Vasteras, Sweden, a corporation of Sweden Filed Mar. 19, 1959, Ser. No. 800,549 Claims priority, application Sweden Mar. 26, 1958 3 Claims. (Cl. 200-448) In applicants US. Patent No. 2,803,724, granted on August 20, 1957 a circuit breaker with contacts arranged inside a compressed air containeris shown. During an opening movement of this circuit breaker the movable contact is retained for a moment at a distance from the stationary contact most suitable for the extinction action and is then, after a short time, moved to a fully open of operation is effected by comp'ressed'airbeing supplied through a pipe line to a space on one side of a piston, for actuating said piston, which is joined by a rod to the movable valve member of a blast valve, which movable member closes the outlet from the container to the open air. As the movable valve member is forced by the rod to open the blast valve, the movable contact is moved in the direction toward the open position by the'compressed air in the container in which the contacts are arranged. Thereby the movable contact meets the movable valvemember in its open position and is pneumatically coupled to it by a special arrangement and, after a delay, forces the valve member is maintained by an arrangement in which the space on the back side of the piston is, through a narrow channel in said piston, in permanent communication with the space which is in direct communication with the pipeline so that the air pressure on both sides of is gradually equalized. With this sequence of operation it is important that the movable valve member opens as fast as possible. As, however, according to the above patent, the space on the back side of the piston is closed but for the channel through thepiston, the air in this space will be compressed when the piston is moved upwards, and consequently will slow down the opening movement of the movable valve member.

The present invention relates to an operating device for a blast valve by which the above mentioned disadvantage is overcome. According to the invention the space on the back side of the piston is in communication with the open air through a channel which can be closed by an outlet valve. This valve is controlled in relation to the position of the piston so that the outlet valve, counteracted by a spring, will first be closed, as the piston has been forced 'by compressed air being supplied to the space on the other side of it, to the end position which corresponds to an open blast valve. After the air pressure according to the above has been equalized on both sides of the piston, said piston is forced back to its other end position by the movable contact. The outlet valve, however, remains closed until the space on the back side of the piston is connected by the channel through the piston and the pipe line to the open air, at which the outlet valve, influenced by the spring opens again. Thus the device automatically makes sure that the blast valve is fully opened before the outlet valve is closed.

The invention will be most readily understood with reference to the accompanying drawings in which FIG- URES 1 and 2 show two different forms of the invention.

In FIGURE 1, a mechanism housing .1 is inserted in the wall of a container 18 which encloses the breaking gap, the movable contact of which is designated by 19. In the lower part of the mechanism housing 1 there is back to the closed position. The delay the piston United States Patent a piston 2 which, by means of a rod 3, is joined to a valve member 4. This valve member 4 is on the lower side provided with an annular shaped packing 5 which, in the lower position, is tightly forced against the annular edges 6 and 7. These edges constitute the blast valve seat. I

The space 8 below the piston 2 is connected to the pipe line 9 and the space 12 over the piston 2 communicates through a channel 10 with the open air. The space 8 communicates through a channel 11in the piston 2 with the space 12. On the rod 3 an axially movable disc 13 is arranged, which disc is provided on its upper SldB with a packing 14. This is in the upper position of the disc 13, tightly forced against the edges 15 and 16. A spring 17 arranged concentrically around the rod 3 enerts a pressure on the disc 13 totorce it against the piston 2. The arrangement acts in'the following way. The circuit breaker is opened by compressed air being supplied through the pipe line 9, at which the piston 2 with the disc 13 and packing 14 is moved upwards so that the packing 5 leaves the tightening edges 6 and 7 and the blast valve opens. The compressed air in the container 18 now forces the movable contact 19 downwards until it meets the valve member 4 in the upper position of the valve member and is pneumatically coupled with said valve member.

. During the upward movement of the piston 2, the air in the space 1-2 is forced out through the open channel 10 to the open air. In the upper position of the piston 2,

the channel 10 is closed due to the disc 13 with the packing 14 being tightly forced against the edges 15 and 16 by the piston v2. As the air in .the space 8 flows through the channel 11 into the space 12 the pressure on the upper side of the piston after some time will be so high that the valve member and the piston 2 are returned to the lower end posit-ion by the movable contact 19 until the packing 5 is again tightly forced against the edges 6 and 7 and The circuit, breaker closes as the pipe line 9 is coni nected to the open air, at which the pneumatic coupling between the valve member 4 and the movable contact 19 ceases and the latter is forced toward the closed position by a spring. At the same time, the disc 13 is disengaged as the air pressure on both sides of it reaches the same level and said disc 13 is returned to its lower position by the spring 17.

FIGURE 2 shows another embodiment of the invention.- The disc 13, the packing of which according to FIGURE 1, is counteracted by a spring and tightly forced against the edges 15 and 16, has here been replaced by another valve 20, which is arranged to close the channel 10 at its outlet opening to the open air. The valve head 21 is operated by a diaphragm 22 which, when compressed air is supplied through a pipe line 23 to its one side, forces the valve head 21, counteracted by a spring 24 to close the channel 10. The pipe line 23 terminates in the operating space of the piston 2 in such a way that it is not directly connected with the pipe line 9 via space 8 until the piston 2 has reached its upper end position.

The arrangement functions in the following way. The circuit breaker is opened by compressed air being suppliedthrough the pipe line 9, and the same operating sequence takes place as described for the device according to FIGURE 1 except that the channel 10 is now closed by another valve (20).

Not until in its upper position has the piston 2 passed the opening of the pipe line 23 to the operating space, at which the pipe line 23 which until then has been in communication via the: channel with the open air, is now filled with compressed air from the pipe line 9. Thereby the opening of the channel 10 is closed by the valve head 21.

When the air in the space 8 flows through the channel 11 into the space 12, an equalization of the pressure between the spaces is obtained after some time, so that the movable contact can force the piston back to its lower end position. The valve 20, however, remains closed until the pipe line 9 is connected With the open air, at which the valve again opens at the same time as the movable contact again closes the breaking gap in the way described above.

The invention is naturally not limited to the above mentioned range of application but can also be used for all valves which are operated by a compressed air operated piston counteracted 'by aspring, the operating movements of which are the same as for the blast valve according to the above. A-lso possible is a reversed sequence of operation so that the valve normally is in the open position and closes when compressed air is supplied to one side of the piston, after which the valve after some time opens again.

I claim:

1. In an air blast circuit breaker comprising a blast valve, operating'means for the valve comprising a piston stantial-lyabove that of the free air, and means independent of said connecting means to connect the second operatively connected thereto and separating first and second spaces, means for supplying compressed air to the first space to move the piston in a first direction, means connecting the second space to free air, means responsive to movement of the piston to its end positionv in said first direction to close said connecting means,

means to equalize the pressures in said two spaces, means operative when the pressures are equalized to move the piston in a second direction, said connection closing means being responsive to pressure in said second space to maintain the connecting means in closed condition when the pressure in said second space remains subspace to free air, said connection closing means being rendered inoperative when the pressure in said second space equals that of the free air.

2. In a circuit breaker as claimed in claim 1, said connection closing means comprising a valve engageable by the piston on movement in said first direction and movable therewith to close the connecting means, said valve being separate from the piston and being held in such closed position by the equalized pressure in said second-space, said independent means comprising means to connect the first space to free air.

3. In an air blast circuit breaker comprising a blast valve, operating means for the valve comprising a cylinder, a piston slidably mounted in' the cylinder dividing it into first and second spaces 'and'a piston rod operatively connecting the piston to the 'blast valve, said cylinder having an opening in the end thereof connecting the second space to free air, a valve slidably mounted on said piston rod in said second space and movable with the piston, when the piston moves in a first direction to contract saidsecond space, to a seated position closing said opening at the end of the movement of the piston in said first direction, means to supply air under pressure to said first space to move the piston in said first direction, said piston having a relatively small opening 'therethrough for equalizingthe pressure in the two spaces after said valve reaches its seatedtposition, a spring normally urging said valve away from its seated position, and means to connect said first space to free air, whereby the pressure in said second space is reduced and the valve moves to open position.

References Cited in the file of this patent UNITED STATES PATENTS 2,803,724 Forwald Aug. 20, 1957 FOREIGN :PATENTS 1,155,626 France Dec. 2, 1957 

